Multi-channel flat tubes and heat exchangers containing such tubes are known in the art. In DE 100 07 159 A1 a cooler and evaporator tube is disclosed that is characterized by a special cross-section of the channels in the flat tube. The number of channels in the flat tube is not given more precise, these channels extending in longitudinal direction of the flat tube.
Further, to DE 197 19 260 C1 a stamped flat tube is known in the art that also consists of several channels and is equipped with additional webs the deformation of which yields a more turbulent flow profile in the channels. Again the channels extend in longitudinal direction of the flat profile.
The heat exchanger configured of such flat tubes combined with fins is passed by air on cross-flowing principle.
Thus the flat tube is transversely passed around. As the flat tube is usually formed of a material that is a good heat conductor, heat conduction along the width of the flat tube inevitably occurs. Reducing the heat transfer efficiency, this proportion of heat transport is not desirable.
The losses are even raised by that neighboring channels of the flat tube are passed in opposite flow directions. The refrigerant flows in opposite flow directions at least once, or several times. Hence high temperature differences can occur between neighboring flow channels that cause high heat conduction losses between the flow channels. Manufacture of heat transfer devices with separate flat tubes that are series-connected in direction of the air flow and have no contact surfaces to each other is very expensive.
The known flat tubes according to the generic term feature high transverse heat conduction and for that reason, are not really suitable for heat transfer devices working on cross flow principle.
From U.S. Pat. No. 5,186,244 a multi-channel flat tube to the generic term is known that is intended to overcome the disadvantage of transverse heat conduction by that the material is tapered to define a web and by indentation of this web. Particularly disadvantageous is the reduced static loadability of said multi-channel flat tube that makes the tube become unstable. Also the increased space requirement of a too wide web is not desired.
The invention is intended to solve the problem to further develop a multi-channel flat tube according to the generic term such that heat exchangers manufacturable of it, particularly cross flow heat exchangers, are characterized by higher heat transfer efficiency while maintaining the mechanical stability of the multi-channel flat tubes.